Quick answer: ADHD and autism overlap far more than most people expect, somewhere between 40 and 70% of people with one condition show meaningful traits of the other, depending on the study. When they show up together, it’s sometimes called AuDHD. In girls, the two can mask each other so well that both go unnoticed for years. Neither one being “worse” than the other. Knowing both are in the picture just means the support can finally fit.
Why autism and ADHD turn up together so often
If you’ve read our first post on ADHD comorbidities, you’ll know that ADHD rarely arrives alone. Autism is one of the conditions it keeps the most company with, and the overlap is bigger than a lot of people assume.
Researchers estimate that somewhere between 50 and 70% of autistic people also meet the criteria for ADHD, and recent studies suggest around 45% of adults with ADHD show significant autistic traits, even when only a tiny fraction have both formally diagnosed. That gap between “shows the traits” and “has the diagnosis” is enormous, and it’s not because the traits aren’t real. It’s because our systems still tend to look for one condition at a time.
Part of the reason the two travel together is genetic. A large genomic study found that ADHD and autism share several regions of genetic risk, meaning a lot of what makes someone likely to have one also makes them more likely to have the other. Brain imaging research backs this up too: people with both conditions show patterns of brain structure and connectivity that are distinct from either condition on its own, not just “ADHD plus autism,” but something closer to its own neurodevelopmental profile.
The double mask: why it’s so easy to miss in girls
Here’s where it gets trickier for girls and young women specifically. Autism is still diagnosed more than three times as often in boys, not because it’s rarer in girls, but because the diagnostic tools were built around how autism tends to look in boys. Add ADHD into that same picture and the gap widens further: women wait, on average, several years longer than men for an ADHD diagnosis in the first place.
When both conditions are present, they can hide each other. This sometimes gets called “double masking.” A girl’s ADHD-driven sociability and quick thinking can make her autistic social difficulties look like nothing more than being chatty or a bit scattered. Meanwhile, an autistic preference for structure and routine can quietly cover up ADHD-related executive dysfunction, because she’s built herself a system that just about holds it together, as long as nothing changes. From the outside, she looks fine. On the inside, she’s often exhausted from working twice as hard to seem like everyone else.
That exhaustion tends to show up as intense emotional reactions, a strong fear of rejection or getting things wrong, swinging between hyperfocus and total avoidance, and a kind of social tiredness that doesn’t match how easily she seems to get on with people. If that sounds like “anxious, a bit much, and never quite keeping up,” rather than a textbook description of either condition, that’s exactly the point. AuDHD often doesn’t look like either condition on its own. It looks like its own thing.
What it can actually look like day to day
There’s no single AuDHD experience, but some patterns come up again and again in the girls and young women we work with:
Wanting connection and structure, but finding both exhausting to maintain. Needing routine to feel safe, while also craving novelty and getting bored fast. Being deeply sensitive to sound, texture, or light, and also chronically losing track of time, objects, or plans. Feeling like she’s performing a version of herself that’s palatable to everyone else, and having no idea who she is underneath that performance by the time she’s a teenager.
None of that means something is wrong with her. It means her brain is managing two different sets of wiring at once, and doing it without much acknowledgement from the world around her that both are real.
Getting the right support
If any of this sounds familiar, whether you’re a young woman reading this about yourself, or a parent or professional recognising a girl you know, the first step is simply naming it. An ADHD diagnosis doesn’t rule autism out, and an autism diagnosis doesn’t rule ADHD out. Plenty of assessment services will consider both if you ask directly, so it’s worth raising it explicitly rather than assuming someone will spot it for you.
Beyond diagnosis, the support that tends to help is the kind that holds both truths at once: routines with enough flexibility built in that they don’t shatter the first time something changes, sensory needs taken seriously rather than dismissed as fussiness, and space to stop performing, even briefly. That’s a lot of what we try to build into our sessions and our community: somewhere the mask can come off for an hour or two.
Find Your Community
If you’re a young woman who’s just recognised some of this in yourself, you don’t have to work it out on your own. Our community is full of girls figuring out the exact same overlap, in their own time and in their own words.
Wish Your Parents or Carers Understood You Better?
We run sessions and resources for parents too, because “she’s just being difficult” and “she’s just autistic-coded ADHD trying to hold it all together” are very different starting points for support. Send this post their way if it would help.
Coming up
Next in this series: ADHD and anxiety, and why the two feed each other more than either one explains alone.
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